2 major decisions near for Los Osos sewer

The county’s Los Osos sewer project will face two key hearings before state water officials in coming months.

On March 1, the State Water Resources Control Board in Sacramento is expected to approve more than $86 million in loans and grants, a significant chunk of the $189 million needed to build the facility.

On May 5, the Central Coast Regional Water Quality Control Board in San Luis Obispo will set the discharge requirements the new sewer system must meet when it goes on line in 2014. These dictate how clean the water must be when it is discharged from the treatment plant.

“These are performance standards,” said David LaCaro, with the Regional Board’s wastewater compliance unit. “We set the standards, and the county designs a plant to meet those standards.”

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One crucial standard is nitrates. The upper aquifer in the Los Osos groundwater basin has unhealthy levels of nitrates from thousands of residential septic systems.

A goal of the sewer system is to inject treated wastewater from the sewer plant into the upper aquifer to lower the nitrate levels, LaCaro said. In order to achieve this, the sewer plant effluent has a limit of 7 milligrams of nitrates per liter. The state drinking water standard is 10 milligrams.

“This is one of the key elements in getting back to a groundwater balance in the region,” LaCaro said.

John Waddell, project manager with the county Public Works Department, said the plant is designed to meet those standards. “This is entirely what we expected,” he said.

The public comment period for the discharge standards closes March 11.

Lining up funding for the project is another important task, Waddell said. The money will come from state and federal sources in nearly equal amounts.

State clean water funding to be considered March 1 would come in the form of low-interest loans and a grant of $7.5 million, Waddell said.

The other major funding source is federal stimulus money from the Department of Agriculture.

That agency has allocated $83 million in loans with a grant of $4 million.

Under this financing scheme, average monthly charges over 30 years will be $194 for single-family homes, $120 for multifamily homes, $55 for mobile homes and $183 for nonresidential lots.

The Los Osos sewer project calls for installing an entire sewage collection and treatment system in the community of 13,538.

More than 41 miles of collection lines will be laid and a 1.2 million-gallon-per-day treatment plant constructed.

County officials hope to begin construction later this year and complete the project in 2014.